The size of the Minoan eruption
Distribution of the Minoan ash
The so-far established size estimations were largely based on field data from Santorini, neighboring islands, from the sea bed, and western Turkey, where the deposit can still be found in lake deposits.
The traditional and to-date most widely accepted value of the erupted magma volume of the Minoan eruption ranges between 30-40 cu km, corresponding to a total tephra volumen of about 80-90 km3, and takes into account various field data obtained and modeling done between around 1970-1990 (e.g. Sigurdsson et al, 1990).
Recently, new outcrops of the Minoan tephra (e.g. 2 m on Anafi Island, on the sea floor around Santorini and elsewhere) have become available. These findings suggest that the eruption could be larger than originally thought, ranking in fact as VEI 7, which would make it perhaps the second largest explosive eruption in historic time on the planet (after Tambora 1815).
The following is the original press release published at the University of Rhode Island about this hypothesis.
Santorini eruption much larger than originally believed
The Minoan pumice layer at the south coast of Santorini
During research expeditions in April and June, the scientists from the University of Rhode Island and the Hellenic Center for Marine Research found deposits of volcanic pumice and ash 10 to 80 meters thick extending out 20 to 30 kilometers in all directions from the Greek island of Santorini.
“These deposits have changed our thinking about the total volume of erupted material from the Minoan eruption,” said URI volcanologist Haraldur Sigurdsson.
In 1991 Sigurdsson and his URI colleague Steven Carey had estimated that 39 cubic kilometers of magma and rock had erupted from the volcano around 1600 B.C., based on fallout they observed on land. The new evidence of the marine deposits resulted in an upward adjustment in their estimate to about 60 cubic kilometers. (The eruption of Mount Tambora in Indonesia in 1815 is the largest known volcanic eruption, with approximately 100 cubic kilometers of material ejected.)
An eruption of this size likely had far-reaching impacts on the environment and civilizations in the region. The much-smaller Krakatau eruption of 1883 in Indonesia created a 100-foot-high tsunami that killed 36,000 people, as well as pyroclastic flows that traveled 40 kilometers across the surface of the seas killing 1,000 people on nearby islands. The Thera eruption would likely have generated an even larger tsunami and pyroclastic flows that traveled much farther over the surface of the sea.
“Given what we know about Krakatau, the effects of the Thera eruption would have been quite dramatic,” said Carey, a co-leader of this year’s expeditions. “The area affected would have been very widespread, with much greater impacts on the people living there than we had considered before.”
Press release by Todd McLeish / University of Rhode Island, republished with kind permission